Active stylus downlink signal transmission timing control relative to sensor controller

The present disclosure relates to a method in which an active stylus and a sensor controller are used, a system, a sensor controller, and an active stylus.

In recent years, as an inputting apparatus for hand-written inputting on a panel of an electronic apparatus, styluses of various types such as the electromagnetic induction type and the capacitance type have been getting used, and a stylus of an active capacitive type is one of such styluses. In the following description, a stylus of the active capacitive type is referred to as “active stylus.”

Transmission of a signal by an active stylus is performed by supplying a transmission signal to an electrode provided at a tip of the active stylus such that a variation of an electric field (alternating electric field) is generated in a space in the proximity of the electrode. An electronic apparatus includes a sensor board including an electrode group disposed in a matrix below a panel and a sensor controller connected to the sensor board, and is configured such that the sensor controller detects a variation of a charge amount generated in the electrode group in the sensor board by the alternating electric field to receive a signal transmitted from the active stylus. Patent Document 1 discloses an example of an active stylus configured such that it transmits a signal modulated with writing pressure information, a unique identifier (ID) and so forth together with a non-modulated continuous signal for position detection. In the following description, a non-modulated signal for position detection is referred to as “position signal,” and a signal modulated with writing pressure information, a unique ID and so forth is referred to as “data signal.”

It is possible for a sensor controller of an electronic apparatus compatible with an active stylus of the active capacitive type also to transmit a signal to the active stylus. The sensor controller supplies a transmission signal to an electrode group that configures a sensor board thereby to generate an electric field on a panel such that a signal can be transmitted toward the stylus. The active stylus is configured such that it detects a variation of the charge amount induced in the electrodes by the electric field by the reception electrodes thereby to detect the signal transmitted from the electronic apparatus. Patent Document 2 discloses an example of an active stylus that receives a signal transmitted from a sensor controller.

A sensor board for detecting an active stylus frequently serves also as a sensor board for detecting a touch of a finger therewith. An electronic apparatus is configured such that a single sensor board for performing detection of a touch of a finger and detection of an active stylus is placed on a liquid crystal panel supplied from a display maker. A system in which a sensor board for performing detection of an active stylus is placed outside a liquid crystal panel in this manner is referred to as system of the “out cell type” for the convenience of description.

It is known that, even where a sensor board exists outside a liquid crystal panel as in a system of the out cell type, a driving signal in the liquid crystal panel existing below the sensor board makes a noise and has an influence on a detection action of a finger by the sensor controller or on a detection action of the active stylus. A representative one of types of such noise is an alternating current component of a voltage signal supplied to an electrode for driving a pixel of the liquid crystal panel. The voltage signal is used to control the orientation of the liquid crystal in each pixel, and enters an electrode group that configure the sensor board through alternating current (AC) coupling and makes noise.

A disclosure is known in which a countermeasure against such noise is performed solely by a sensor controller. Patent Document 3 discloses that a signal from which noise is cancelled can be obtained by a differential signal between a signal detected by an electrode in touch detection of a finger and a signal detected by a dummy electrode provided around the electrode and including a noise component. Patent Document 4 discloses a method in which a horizontal synchronizing pulse of a display apparatus is generated in a known cycle while the phase thereof is controlled and a position signal or a data signal from a finger or a stylus is detected from a timing synchronized with the pulse. Further, Patent Document 2 discloses that a stylus measures the level of a reception signal and a signal and a noise are identified from each other on the basis of a time length of a period within which the level is high.

Further, in recent years, a liquid crystal panel that performs touch detection of a finger of the on cell type or the in cell type has become popular (refer to Non-Patent Document 1). In the liquid crystal panel of the on cell type, an electrode group for a touch sensor is arranged on a color filter glass plate or a substrate glass plate in the inside of the liquid crystal panel, and electrodes configuring the liquid crystal panel and electrodes configuring the sensor board are separate electrodes. Since the distance between the electrodes is smaller than that of the out cell type described hereinabove, the electrodes for the touch sensor are influenced significantly by noise from the electrodes for liquid crystal driving.

On the other hand, in a liquid crystal panel of the in cell type, a common electrode or a pixel electrode (hereinafter referred to as commonly used electrode) of the liquid crystal panel is used as part of an electrode group for touch detection of a finger or for detection of an active stylus. While a driving action of pixels is performed in the liquid crystal panel, the potential of the commonly used electrode that is used commonly also for touch detection is set to a potential for pixel driving (which may be fixed or may be variable). Accordingly, in the liquid crystal panel of the in cell type, in the first place, while a driving action of pixels is being performed, the sensor controller cannot receive a signal from the active stylus.

Patent Document 1: PCT Patent Publication No. WO2015/111159 Patent Document 2: U.S. Patent Application Publication No. 2013/0106797 Patent Document 3: Japanese Patent Laid-Open No. 1993-6153 Patent Document 4: PCT Patent Publication No. WO2015/141349

Non-Patent Document 1: “In cell/on cell strategy for smartphones of JDI, LG, Sharp is read,” [online], Nikkei Technology Online, [searched on Mar. 8, 2016], Internet <URL: http://techon.nikkeibp.co.jp/article/NEWS/20150121/400160/>

In detection of a touch of a finger, even if a sensor controller solely stops a detection action of a touch of a finger within a period within which much noise is generated in a system of the out cell type (or of the on cell type) or within a liquid crystal driving period of a liquid crystal panel of the in cell type (those periods are hereinafter referred to each as “display refresh period”), although a detection rate of a position signal drops, missing of information does not occur. This is because, as long as a finger exists on the sensor board exceeding a single display refresh period equal to or smaller than several milliseconds, information indicating that a finger exists (or does not exist) does not suffer from missing.

However, if, in detection of an active stylus that transmits a data signal modulated with data of a writing pressure value, a unique ID or the like, the sensor controller uniquely stops a detection action within the period in response to a generation situation of liquid crystal noise or an action situation thereof, then a case occurs in which part of information transmitted from the active stylus within the period cannot occasionally be transmitted. For example, when the active stylus continues to repetitively transmit a position signal and a data signal like the active stylus disclosed in Patent Document 1, if the data signal is received within a display refresh period, then part of data included in the data signal will miss.

Especially, a sensor controller in which an electrode commonly used with a touch sensor is provided in the inside of a liquid crystal panel of the in cell type and is utilized comes to have an increased variety in regard to an appearance frequency and a length of a display refresh period in response to an action mode of the liquid crystal panel, a refresh rate, various action modes regarding in which region a commonly used electrode is used for driving of a pixel and so forth, settings, and a configuration of electrodes. Further, similarly to a liquid crystal panel of the in cell type, within what period a display refresh period appears in display panels such as an organic electroluminescence (EL) panel in which some of driving electrodes are commonly used with a touch sensor or a display panel of a special shape used together with a digital signage or the like depends upon a configuration and action of the display panels.

In order to make it possible for a sensor controller, which is incorporated in a system that uses a display panel of the in cell type or a display panel that acts in various display refresh periods, to detect a signal transmitted from an active stylus, which is in a pen down operation state, as soon as possible and receive information of a writing pressure and so forth put on a data signal without missing in the future, it is desirable to make it possible to transmit a preferable transmission timing for a signal in response to a refresh or a setting state of the display panel from the sensor controller to the active stylus such that the active stylus can transmit a predetermined signal avoiding a display refresh period unique to the display panel.

Accordingly, one object of the present disclosure resides in provision of a method in which an active stylus and a sensor controller are used, a system, a sensor controller, and an active stylus by which a preferable transmission timing of a signal according to a refresh state of a display panel can be conveyed from a sensor controller to an active stylus.

A method according to the present disclosure in which a sensor controller is connected to a sensor having an electrode group provided together with a display panel configured to operate in a variable refresh cycle among a plurality of refresh cycles, and an active stylus performs bidirectional communication with the sensor controller. According to the method, the sensor controller acquires a present refresh cycle among the plurality of refresh cycles of the display panel, generates an uplink signal, which serves as a reference for synchronization corresponding to the acquired refresh cycle, and transmits the uplink signal to the active stylus, which is not detected as yet or is detected already, at the present refresh cycle.

A system according to the present disclosure includes a sensor controller connected to a sensor having an electrode group provided together with a display panel configured to operate in a variable refresh cycle among a plurality of refresh cycles, and an active stylus that performs bidirectional communication with the sensor controller. The sensor controller transmits an uplink signal, which serves as a reference for synchronization corresponding to the present refresh cycle among the plurality of refresh cycles of the display panel and serves as a reference that designates a time point at which the active stylus is to transmit a downlink signal, to the active stylus that is not detected as yet or is detected already at the refresh cycle. The active stylus, in operation, detects the uplink signal, transmits the downlink signal at the time point designated by the reference included in the detected uplink signal. The sensor controller detects the active stylus by detecting the downlink signal.

A sensor controller according to the present disclosure is connected to a sensor having an electrode group provided together with a display panel configured to operate in a variable refresh cycle among a plurality of refresh cycles and perform bidirectional communication with an active stylus. The sensor controller includes a transmission circuit, and a control circuit that, in operation, specifies a present refresh cycle among the plurality of refresh cycles of the display panel and causes the transmission circuit to transmit an uplink signal, which serves as a reference for synchronization of a transmission of a downlink signal corresponding to the specified refresh cycle, to the active stylus.

An active stylus according to the present disclosure performs bidirectional communication with a sensor controller connected to a sensor having an electrode group provided together with a display panel that displays images during a plurality of refresh cycles. The active stylus includes a reception circuit that, in operation, receives from the sensor controller an uplink signal that serves as makes a reference for synchronization transmitted repetitively at a present refresh cycle among the plurality of refresh cycles of the display panel, and a transmission circuit that, in operation, transmits a downlink signal to the sensor controller at a time point designated by the uplink signal.

According to the present disclosure, since the sensor controller acquires a signal indicating a present refresh cycle of the display panel, it is possible to transmit, from the sensor controller to the active stylus, an uplink signal that serves as a reference to synchronization corresponding to the refresh cycle indicated by the acquired signal. Accordingly, to the active stylus that sends back a downlink signal at a timing designated as a reference time point for synchronization given by the uplink signal or transmits a downlink signal cyclically, a preferable transmission timing for a signal according to a state of the display panel can be conveyed.

In the following, embodiments of the present disclosure are described in detail with reference to the accompanying drawings. First, as a first embodiment, a case in which the present disclosure is applied to a system of the out cell type is described. Thereafter, as a second embodiment, a case in which the present disclosure is applied to a system of the in cell type is described.

1 FIG. 1 1 1 2 0 3 31 2 34 33 30 31 3 33 32 30 33 32 is a schematic view of a position inputting systemaccording to the first embodiment of the present disclosure. The position inputting systemis a system that utilizes a stylus of the active capacitive type. The position inputting systemis configured including a stylus(active stylus) for inputting an indication position P (Pthrough Pk through Pn) and operation state data OD of a writing pressure and so forth to the electronic apparatus, and a sensor controllerthat derives an indication position P of the stylusat present using a sensor boardplaced on the liquid crystal paneland outputs the indication position P to an electronic apparatus control circuittogether with the operation state data OD. The sensor controlleris provided in the electronic apparatusthat includes a liquid crystal paneland a liquid crystal driving circuit, and an electronic apparatus control circuitthat controls the liquid crystal paneland the liquid crystal driving circuit.

2 31 31 2 2 31 The stylusis a stylus of the active capacitive type including a power supply, a communication circuit and electrodes for detecting an uplink signal US transmitted in a predetermined cycle from the sensor controllerand transmitting a downlink signal DS at a time point indicated as a reference time point given by the detected uplink signal US. The indicated time point is either (1) a time point designated in advance before the sensor controllerdetects the stylus(hereinafter determined as time point immediately after the uplink signal US) or, after the stylusand the sensor controllerdetect each other, (2) a time point designated expressly as a reference time point given by the uplink signal US in accordance with a command CC_UP included in the uplink signal US.

2 2 31 31 2 The downlink signal DS includes a position signal D_DP indicating that the stylusexists at a position at which it is detected and a data signal OD_DP modulated with data such as operation state data OD or the like such as writing pressure information. The position signal D_DP is utilized also as a response signal with which the stylusresponds to an uplink signal US hereinafter described transmitted from the sensor controllerto allow the sensor controllerto detect the stylus. In the following description, where the position signal D_DP and the data signal OD_DP are not distinguished from each other, they are collectively referred to as downlink signal DS.

31 34 33 33 2 34 31 32 2 31 2 30 The sensor controlleris an integrated circuit (IC) that is connected to the sensor boardprovided in an opposing relationship to the liquid crystal panelin a normal direction to the liquid crystal paneland performs communication with the stylusthrough the sensor board. The sensor controllermanages the cycle and the time period for transmitting an uplink signal US on the basis of a refresh state of the liquid crystal driving circuit, transmits an uplink signal US in accordance with the cycle and the time period, and detects a downlink signal DS transmitted at a reference time point given by the uplink signal US, thereby detecting the stylus. Further, the sensor controllerderives an indication position P of the styluson the basis of the detection position, extracts operation state data OD of a writing pressure and so forth from data included in the data signal OD_DP and supplies the operation state data OD to the electronic apparatus control circuittogether with the indication position P.

33 33 1 FIG. The liquid crystal panelincludes a plurality of pixels arranged in a matrix along two directions in which a panel face is formed (an X direction and a Y direction depicted in). Each pixel is configured including a pixel electrode and liquid crystal. The liquid crystal panelis configured further including a polarizer, a glass substrate, a color filter, a common electrode, a backlight light source and so forth. Among the components mentioned, the common electrode is provided for each region where the panel face is divided into a plurality of regions, and within a display refresh period, a fixed or variable voltage is applied to the common electrode such that a potential difference according to a value of a pixel is formed between the common electrode and the pixel electrode.

32 30 33 33 31 2 33 34 1 FIG. The liquid crystal driving circuitgenerates a driving signal LD (gate-source voltage or the like) on the basis of a video signal V supplied from the electronic apparatus control circuit. The driving signal LD plays a role of controlling polarization of liquid crystal of each pixel in the liquid crystal panelto display a video image according to the video signal V. The driving signal LD includes a component of a high frequency, and every time the driving signal LD is supplied to the liquid crystal panel, liquid crystal noise LCDnz is included also in a signal to be received by the sensor controllerthrough a parasitic capacitance (represented by Cin) formed between the liquid crystal paneland the sensor board.

1 2 Now, an outline of action of the position inputting systemis described in light of a typical operation method of the stylusby a user.

2 2 35 2 35 2 34 0 34 2 2 31 2 31 31 2 31 2 1 FIG. 1 FIG. When the stylusis to be operated, the user would perform an operation for moving the stylustoward an operation panel(pen down operation). The movement of the stylusby the pen down operation is a space movement including a component in a normal direction to the operation panel(Z direction depicted in). When the styluscomes near to the sensor boardin the proximity of an indication position Pas depicted in, a sufficient coupling capacitance C for transmitting and receiving a signal is formed between an electrode group configuring the sensor boardand a tip of the stylus. The stylusis enabled to detect an uplink signal US transmitted from the sensor controllerthrough the coupling capacitance C. The stylusperforms an internal process for synchronizing with the uplink signal US and transmits a downlink signal DS at a time point designated by the sensor controllerwith reference to a reference time point given by the uplink signal US (for example, at a time point immediately after the reference time point). If the sensor controllersuccessfully receives a downlink signal DS transmitted from the styluswithout being influenced by noise LCDnz or the like, then the sensor controllercan start processes for detection of the stylus, derivation of the indication position P and so forth.

2 0 2 35 2 1 FIG. After the pen down operation, the user would move the tip of the stylusin such a manner as to draw a locus Path, for example, from Pto Pn depicted inin a state in which the tip of the stylusis kept in contact with the operation panel. During the period, the stylusrepeats transmission of a position signal D_DP and a data signal OD_DP at each time point indicated on the basis of the reference time point given by the uplink signal US. Within the period, the value of the coupling capacitance C has a comparatively high value in comparison with that upon pen down.

2 35 31 2 2 31 2 31 2 31 The user would perform an operation for removing the tip of the stylusfrom the operation panel(pen up operation). The pen up operation is an operation reverse to the pen down operation. If the sensor controllerand the stylusare spaced away from each other to such a degree that a sufficient coupling capacitance C is not formed any more in the proximity of the indication position Pn, then transfer of a signal between the stylusand the sensor controlleris disabled. Even after the transfer is disabled, for a fixed time period, the reference time point and the cycle are maintained as an internal state of each of the stylusand the sensor controller. After the fixed time period elapses, the reference time point as an internal state of each the stylusand the sensor controlleris canceled.

31 2 2 2 2 31 31 2 If the sensor controllerfails to detect a downlink signal DS transmitted from the stylusbecause of liquid crystal noise LCDnz although the stylusundergoes a pen down operation and exists within a detectable range irrespective of whether this is caused by the fact that the styluscannot detect an uplink signal US or by the fact that a downlink signal DS sent back from the styluscannot be detected by the sensor controller, then the time point at which the sensor controllerdetects the stylusis delayed at least to next transmission of an uplink signal US.

2 31 31 30 2 2 35 1 That detection of the stylusby the sensor controlleris delayed causes a delay of succeeding processes such as, for example, a coordinate detection process by the sensor controller, a cursor displaying process of a coordinate position by the electronic apparatus control circuitand so forth. Here, the time point at which the stylusperforms the pen down operation is a time point at which the user starts utilization of the styluson the operation panel, and the delay of a succeeding displaying process causes a response delay of the position inputting system, which is experienced by the user.

2 2 31 31 2 Therefore, it is an object of the present embodiment that, when the user performs a pen down operation of the stylusuntil the stylusenters the detectable range of the sensor controller, the sensor controllercan detect the stylusat an early stage with a higher probability.

31 33 2 2 In particular, the sensor controllertransmits an uplink signal US in a cycle (refresh cycle VT) of a refresh of the liquid crystal panelto the stylussuch that a downlink signal DS is transmitted from the stylusafter every generation cycle of a blank period BP within which the amount of the liquid crystal noise LCDnz is comparatively small.

2 FIG. 2 FIG. 2 2 20 21 22 23 24 25 26 27 28 is a schematic block diagram depicting function blocks of the stylus. As depicted in, the stylusis configured including an electrode, a transmission/reception switching circuit, an oscillation circuit, a transmission circuit, a reception circuit, an operation information detection circuit, an operation inputting circuit, a configuration information storage device, and a communication control circuit.

20 21 20 23 24 28 21 The electrodeis a conductor in which charge corresponding to a downlink signal DS or an uplink signal US is induced. The transmission/reception switching circuitis a switch for switching a connection state between the electrodeand the transmission circuitor the reception circuiton the basis of a switching signal S_sel supplied from the communication control circuit. The transmission/reception switching circuitis used to perform switching between transmission and reception time-divisionally.

22 31 2 28 The oscillation circuitis an oscillation circuit that generates a carrier signal of a frequency to be used for communication between the sensor controllerand the styluson the basis of a frequency setting signal F_sel supplied from the communication control circuit. The carrier signal may be a sine wave or a rectangular wave of a clock pulse.

24 20 28 The reception circuitis configured such that it extracts a search pattern D_UP or a command CC_UP included in a signal by detecting and demodulating a variation (signal) of a charge amount induced in the electrodeand outputs the extracted search pattern D_UP or command CC_UP to the communication control circuit. Where modulation using a spread code is performed (details are hereinafter described in connection with the second embodiment) as a modulation method for the uplink signal US, a correlation arithmetic operation between a received signal and a spread code stored in advance is performed by a correlator to extract a search pattern D_UP or a command CC_UP.

23 28 20 31 22 22 The transmission circuitgenerates a downlink signal DS on the basis of data supplied from the communication control circuitand supplies the downlink signal DS to the electrodethereby to transmit the downlink signal DS to the sensor controller. When a position signal D_DP is to be transmitted, a carrier signal provided from the oscillation circuitis outputted as it is without being modulated. When a data signal OD_DP is to be transmitted, data such as the operation state data OD, configuration data CD or the like is encoded to generate a transmission digital signal, and a carrier signal provided from the oscillation circuitis modulated with the transmission digital signal to generate a data signal OD_DP.

25 2 26 2 2 28 The operation information detection circuitacquires operation state data OD that is dynamic data that varies in response to an operation state of the stylussuch as an operation state such as on/off of the operation inputting circuitthat is a pushbutton or the like provided on a side face of the stylus, a value of a writing pressure F detected by a writing pressure detection circuit not detected or remaining amount data of a battery serving as a driving power supply for the stylus, and suitably supplies the operation state data OD to the communication control circuit.

27 2 2 2 26 28 The configuration information storage deviceholds, in addition to a stylus identifier SID, configuration data CD that is static data that does not vary in response to an operation state of the stylussuch as a vendor ID indicative of a maker of the stylus, a type of the pen tip of the stylus(ballpoint pen, brush or the like), the number of operation inputting circuitsand so forth and supplies the configuration data CD to the communication control circuit.

28 23 31 24 31 2 2 31 31 2 28 23 28 The communication control circuitcontrols the transmission circuitsuch that a downlink signal DS is transmitted at a time point indicated by the sensor controllerwith reference to a reference time point given by a reception time point of an uplink signal US detected by the reception circuitafter a pen down operation is started. The indicated time point is, within a time period until the sensor controllercompletes detection of a stylus, (1) a time point determined in advance between the stylusand the sensor controller, and particularly a time point immediately after an uplink signal US including a search pattern D_UP is detected (a switching gap between transmission and reception may be interposed). On the other hand, after the sensor controllerdetects a stylus, the indicated point of time is a time point designated expressly with reference to a reference time point given by the uplink signal US by a command CC_UP included in the uplink signal US. In the case of (2), the communication control circuitcontrols the transmission circuitto transmit a data signal OD_DP including data designated by the command CC_UP (including operation state data OD or configuration data CD). Further, the communication control circuitholds a communication setting table and holds a timing of a reference time point detected once, a time period to be used for communication (time slot or the like), a frequency or the like.

3 FIG. 31 34 33 is a schematic block diagram depicting function blocks of the sensor controller. The system of the present embodiment corresponds to that of the out cell type. The sensor boardis placed outside (above) the liquid crystal panelwith a transparent adhesive layer or the like interposed therebetween.

34 45 46 35 45 46 33 45 33 1 FIG. The sensor boardincludes a row electrode groupand a column electrode grouparranged two-dimensionally in such a manner as to form a plane parallel to the operation paneldepicted in. The row electrode groupand the column electrode groupare provided separately from the electrodes that configure the liquid crystal panel(pixel electrodes and common electrodes). A signal appearing in the row electrode groupincludes liquid crystal noise LCDnz generated in the liquid crystal panel.

31 34 47 40 41 42 43 44 3 FIG. The sensor controlleris an integrated circuit connected to the sensor boardand is configured, as depicted in, including a transmission/reception switching circuit, an oscillation circuit, a transmission circuit, a reception circuit, an indicator detection circuit, and a refresh cycle acquisition circuit.

47 45 41 42 43 43 2 43 47 45 41 43 2 47 45 42 The transmission/reception switching circuitis a switch group for switching a connection state between the electrodes configuring the row electrode groupand the transmission circuitor the reception circuithereinafter described on the basis of a switching signal S_sel supplied from the indicator detection circuit. The switching signal S_sel is a signal for instructing, within a time period within which the indicator detection circuitis to transmit an uplink signal US toward the stylus(and when the indicator detection circuitis to perform detection of a finger touch), the transmission/reception switching circuitto connect the row electrode groupto the transmission circuit, but instructing, when the indicator detection circuitis to receive a signal from the stylus, the transmission/reception switching circuitto connect the row electrode groupto the reception circuit.

40 43 The oscillation circuitis an oscillation circuit that generates a signal of a sine wave (or a rectangular wave) of a frequency based on a frequency setting signal F_sel supplied from the indicator detection circuit.

41 40 43 43 45 The transmission circuitmodulates a carrier signal provided from the oscillation circuitwith a search pattern D_UP and a command CC_UP supplied from the indicator detection circuitat a timing indicated by the indicator detection circuitand outputs an uplink signal US to the row electrode group.

42 43 43 42 43 43 The reception circuitexecutes a reception action of a downlink signal DS of the indicator detection circuitat a timing indicated by the indicator detection circuit. If a downlink signal DS is detected within a reception period, then the reception circuitextracts operation state data OD and so forth included in a data signal OD_DP and supplies the operation state data OD to the indicator detection circuit, and acquires position information Pos indicative of an electrode by which a downlink signal DS corresponding to the data signal OD_DP is received and supplies the position information Pos to the indicator detection circuit.

44 32 33 32 7 FIG. 4 7 FIGS.and 7 FIG. The refresh cycle acquisition circuitis a functioning circuit that specifies, on the basis of a driving signal LD or a refresh rate Rr outputted from the liquid crystal driving circuit, a situation of the monitored liquid crystal noise LCDnz or the like, a refresh cycle VT (refer to) indicative of a cycle of control of the liquid crystal panelby the liquid crystal driving circuitand a blank period BP (refer to) that is a period within which the appearance frequency of the liquid crystal noise LCDnz is reduced (becomes sparse in comparison with that within any other period) within the refresh cycle VT. The blank period BP is a period remaining when a display refresh period is removed from the refresh cycle VT corresponding to the refresh rate Rr and is, in the present embodiment, a vertical blanking period VB as hereinafter described with reference to.

3 FIG. 32 31 32 44 32 32 In such a position inputting system of the out cell type as depicted in, the liquid crystal driving circuitand the sensor controllerare configured from integrated circuits separate from each other designed independently of each other, and terminals for extracting the driving signal LD or the refresh rate Rr may not necessarily be provided on the liquid crystal driving circuit. Therefore, the refresh cycle acquisition circuitreceives supply of the driving signal LD or the refresh rate Rr from the liquid crystal driving circuitwhen this is possible and extracts a refresh cycle VT and a blank period BP from the driving signal LD or the refresh rate Rr but detects, when it cannot receive supply of the driving signal LD or the refresh rate Rr from the liquid crystal driving circuit, it monitors the liquid crystal noise LCDnz to detect the density of the liquid crystal noise LCDnz thereby to extract a refresh cycle VT and a blank period BP.

43 2 44 1 43 The indicator detection circuitallocates a communication resource for detecting a stylusnot detected as yet within a refresh cycle VT and a blank period BP acquired by the refresh cycle acquisition circuitand stores the communication resource into a communication resource table CRTb. Further, the indicator detection circuitperforms control for transmitting an uplink signal US including a search pattern D_UP for each refresh cycle VT using the allocated communication resource.

2 2 2 The search pattern D_UP is data including a bit pattern known to the stylusand is data in which 0 or 1 successively appears or 0 and 1 repetitively appear alternately. If the uplink signal US generated by modulation with the search pattern D_UP is a signal that provides a reference timing for synchronization to the stylusthat is to detect the uplink signal US, then the bit length or the substance of the search pattern D_UP does not matter. The uplink signal US that includes a search pattern D_UP including one bit or a plurality of bits makes a signal for instructing the stylusto transmit a downlink signal DS immediately with reference to a reference time point given by the reception time point of the uplink signal US.

43 44 0 1 The indicator detection circuitmay determine, on the basis of action mode information indicative of the refresh cycle VT and the blank period BP extracted by the refresh cycle acquisition circuitor the like, one transmission cycle from among transmission cycles of a finite number of uplink signals US set in advance for the action mode information or the like (cycle of a time slot S). The transmission cycle of the uplink signal US determined from among the plurality of refresh cycles VT in this manner makes one component of communication resources stored in the communication resource table CRTbin addition to the blank period BP.

43 2 2 1 43 2 2 The indicator detection circuitallocates, after it detects a stylus, a time period within which a position signal D_DP and a data signal OD_DP are to be transmitted to the stylusdetected already and stores the time period into the communication resource table CRTb. Further, the indicator detection circuittransmits an uplink signal US that includes the command CC_UP for indicating the substance of data to be transmitted such as the position signal D_DP, the data signal OD_DP or the like and a timing at which the signals are to be transmitted from the stylus(timing determined with reference to the reception timing of the uplink signal US) to the stylus.

4 FIG. 4 FIG. 33 is a view illustrating an example of a relationship between the driving signal LD and the liquid crystal noise LCDnz in a certain one liquid crystal panel. A view at the upper side inis a partial enlarged view of a signal waveform diagram depicted at the lower side.

4 FIG. 4 FIG. 34 The signal waveform diagram ofdepicts an example of a result of measurement of waveforms of a horizontal synchronizing signal HSYNC that is a kind of a driving signal LD and liquid crystal noise LCDnz detected on the sensor boardin response to the horizontal synchronizing signal HSYNC. In, the axis of abscissa indicates the time, and the axis of ordinate indicates the level of a signal.

33 1 2 1 2 4 FIG. The horizontal synchronizing signal HSYNC typically is a signal that conveys a start and an end of a display period when a belt-shaped video image line is displayed on the liquid crystal paneland is a signal in which a rising edge Eand a falling edge Erepetitively appear in a horizontal synchronization cycle HI as illustrated in a view at the upper side in. The rising edge Eindicates a start of a display period, and the falling edge Eindicates an end of a display period.

34 1 2 1 2 4 FIG. 4 FIG. As described hereinabove, a high frequency component of the driving signal LD becomes liquid crystal noise LCDnz to the sensor board. Since the rising edge Eand the falling edge Eare locations at which the horizontal synchronizing signal HSYNC has a high frequency, liquid crystal noise LCDnz is generated at the edges as depicted in the view at the upper side in. More particularly, a state in which the liquid crystal noise LCDnz is great continues over an arbitrary noise period ND from each the rising edge Eand the falling edge E. In contrast, within a period between adjacent noise periods ND, namely, within a noise-free period NF depicted in, the level of the liquid crystal noise LCDnz is so small that it can be ignored.

4 FIG. 5 FIG. 33 The horizontal synchronization cycle HI is variable and sometimes indicates a generally long period or a generally short period as depicted in a view at the lower side in. This arises from the fact that a non-displaying area is provided at part of the liquid crystal panel. In the following, this is described in detail with reference to.

5 FIG. 5 FIG. 5 FIG. 33 33 32 32 is a view depicting a display face of the liquid crystal panel. An outer frame inindicates the whole display face, and a frame of a broken line indicates a display area DA in which a video image is to be displayed effectively. A region between an outer edge of the display face and the display area DA is a non-displaying area in which a video image is not actually displayed although it is included in the display face. Portions of the non-displaying area above and below the display area DA are particularly indicated inas vertical direction non-displaying areas NDA by slanting lines. At least in the liquid crystal panelfabricated at present, such a non-displaying area inevitably appears. The horizontal synchronization cycle HI is relatively short when the liquid crystal driving circuitis generating a horizontal synchronizing signal HSYNC corresponding to the display area DA but is relatively long while the liquid crystal driving circuitis generating a horizontal synchronizing signal HSYNC corresponding to each vertical direction non-displaying area NDA (within a vertical blanking period VB (Vertical Blanking)).

33 32 32 33 4 FIG. In the example of the liquid crystal panelindicated by the example in, the noise-free period NF is relatively short (noise-free period NF_Dense depicted) while the liquid crystal driving circuitis generating a horizontal synchronizing signal HSYNC corresponding to the display area DA but is relatively long (noise-free period NF_Sparse depicted) while the liquid crystal driving circuitis generating a horizontal synchronizing signal HSYNC corresponding to each vertical direction non-displaying area NDA. In such a liquid crystal panelas just described, within a frame period of one image, a noise period NP (display refresh period) within which the generation frequency of liquid crystal noise LCDnz is relatively high and at least one blank period BP (period within which the generation frequency of liquid crystal noise LCDnz is relatively low) exist.

33 4 FIG. Here, in the example of the liquid crystal panelof, the level of the horizontal synchronizing signal HSYNC within the blank period BP indicates a generally high (High) state. However, this is an example to the last, and also an example in which the level of the horizontal synchronizing signal HSYNC within the blank period BP becomes a low (Low) state exists.

6 FIG. 4 FIG. 6 FIG. is a view illustrating a relationship between the driving signal LD and the liquid crystal noise LCDnz in such an example as just described. Also in this example, similarly as in the example in, a period within which the noise-free period NF becomes a noise-free period NF_Dense corresponding to the display area DA and a period within which the noise-free period NF becomes a noise-free period NF_Sparse corresponding to a vertical direction non-displaying area NDA appear alternately as viewed on the time axis. The latter corresponds to a blank period BP in which the liquid crystal noise LCDnz is relatively small. Further, the level of the horizontal synchronizing signal HSYNC within the blank period BP is low (Low) as depicted in.

33 34 33 Although the characteristics of the driving signal LD differs according to the type of the liquid crystal panelin this manner, for the liquid crystal noise LCDnz detected by the sensor board, a noise period NP within which noise is generated relatively densely and a blank period BP within which noise is generated relatively sparsely exist in a cycle of the refresh rate Rr. Further, it is expected that, within a cycle of the refresh rate Rr, at least one blank period BP corresponding to the vertical blanking period VB exists. Here, the appearance interval and the duration of the blank period BP differ depending upon the refresh rate Rr set at present in the liquid crystal panel.

44 32 43 44 In the following description, the refresh cycle acquisition circuitis configured such that it receives supply of a refresh rate Rr from the liquid crystal driving circuitand selects one of a plurality of refresh cycles VT stored therein on the basis of a refresh rate Rr supplied thereto. Further, the indicator detection circuithas stored therein a plurality of transmission cycles for an uplink signal US in advance as described hereinabove and selects one of the transmission periods in response to the refresh cycle VT selected by the refresh cycle acquisition circuit. Then, transmission of an uplink signal US is performed in accordance with the selected transmission cycle.

7 FIG. 33 is a view depicting a relationship between the refresh rate Rr of the liquid crystal paneland the transmission cycle of the uplink signal US.

1 33 33 1 1 1 4 2 33 33 2 2 11 13 7 FIG. 7 FIG. A period T_Rrdepicted inis a period within which the refresh rate Rr of the liquid crystal panelis a first rate of 60 Hz (60 p). The refresh cycle VT of the liquid crystal panelwithin this period is a first refresh cycle VT. A particular value of the first refresh cycle VTis the reciprocal of the first rate and is, for example, where the first rate is 60 Hz, approximately 16.7 milliseconds. Images Pto Pindicate images displayed with this period. Further, a period T_Rrdepicted inis a period within which the refresh rate Rr of the liquid crystal panelis, for example, a second rate of 48 Hz (48 p). The refresh cycle VT of the liquid crystal panelwithin this period is a second refresh cycle VT. A particular value of the second refresh cycle VTis the reciprocal of the second rate and is, for example, where the second rate is 48 Hz, approximately 20 milliseconds. Images Pto Pindicate images displayed within this period.

7 FIG. 7 FIG. 33 33 1 4 11 13 1 4 11 13 As can be recognized from, an image displayed on the liquid crystal panelis updated in a cycle equal to the refresh cycle VT of the liquid crystal panel. Further, every time the image is updated, a blank period BP within which the occurrence interval of the liquid crystal noise LCDnz is sparse appears at least once. In, the blank periods BP corresponding to the images Pto Pand Pto Pare depicted as blank periods BPto BPand BPto BP, respectively.

1 1 7 FIG. A communication resource table CRTbdepicted at the lower side indepicts a relationship between the refresh cycle VT and the transmission timing of the uplink signal US. In the communication resource table CRTb, the horizontal direction indicates a time slot (however, only a portion is depicted schematically) and the vertical direction indicates a communication frequency.

31 700 2 700 0 1 1 1 2 2 2 7 FIG. 7 FIG. The sensor controlleris configured such that it transmits an uplink signal US at a transmission timingdepicted inin order to detect a stylus. In the example depicted in, the transmission timingis transmitted using a time slot Sin which a blank period BP exists from within each refresh cycle VT, and accordingly, the transmission cycle of the uplink signal US is equal to the refresh cycle VT. For example, within the period T_Rrwithin which the refresh cycle VT is the first refresh cycle VT(for example, approximately 16.7 milliseconds), also the transmission cycle of the uplink signal US is VT(for example, approximately 16.7 milliseconds), but within a period T_Rrwithin which the refresh cycle VT is the second refresh cycle VT(for example, approximately 20 milliseconds), also the transmission cycle of the uplink signal US is VT(for example, approximately 25 milliseconds). Though not depicted, where the refresh rate Rr is set such that the refresh cycle VT becomes shorter (for example, 120 Hz or 240 Hz), also the transmission cycle of the uplink signal US becomes a shorter value accordingly.

7 FIG. 1 2 33 In, a period T_Rr_chng indicated between the period T_Rrand the period T_Rrindicates a time period that is required in order to change the refresh rate Rr from the first rate to the second rate. It is to be noted that such a change of the refresh rate Rr (cycle of a rendering timing) occurs, for example, when the action mode of the liquid crystal panelis changed to a power saving mode or the like or when the generation rate fps of an image frame is raised in order to perform smoother display to raise the refresh rate Rr to 120 Hz, 240 Hz or the like.

8 FIG. 8 FIG. 1 33 1 0 1 2 0 19 is a view illustrating an example of the communication resource table CRTbthat indicates a refresh cycle VT of the liquid crystal paneland a resource of communication allocated to a transmission or reception action in the position inputting system. In the example of, communication resources are managed by frequencies f, f, and fand 20 time slots Sto Sas an example. This slot number varies depending upon the refresh cycle VT.

8 FIG. 700 2 719 2 701 702 2 indicates a transmission timingof an uplink signal US including a search pattern D_UP for detecting a stylus, a response timingfor allowing a stylusnot detected as yet to respond to an uplink signal US and transmission timingsandfor allowing a stylusdetected already to transmit a position signal D_DP or a data signal OD_DP including operation state data OD.

8 7 FIGS.and 700 0 700 33 31 31 2 0 As depicted in, the transmission timingof the uplink signal US is given to the time slot Swithin the blank period BP. The cycle to which the transmission timingis given (transmission cycle of the uplink signal US) varies depending upon the refresh rate Rr of the liquid crystal paneland is determined once after the sensor controlleris activated or reset such that it coincides at least with one blank period BP. The sensor controllerperforms transmission of an uplink signal US including a search pattern D_UP for a time period until a stylusis detected using the time slot Scorresponding to a blank period BP for each cycle of the refresh rate Rr.

719 2 1 719 The response timingis a timing at which, after a stylusdetects an uplink signal US including a search pattern D_UP, it responds to the uplink signal US immediately after a reference time point given by the uplink signal US. The reason why the uplink signal US is given to the time slot Simmediately after the uplink signal US is transmitted is that it is intended to cause the response timingto be included in the blank period BP.

2 31 0 2 1 If a stylusthat is not detected by the sensor controlleras yet receives the uplink signal US through the time slot S, then it transmits, as a response signal to the uplink signal US, a position signal D_DP, which is a downlink signal DS for indicating presence of the stylusitself, through the time slot Simmediately after then.

719 1 0 0 31 2 2 35 2 2 701 By fixedly setting the response timingto the time slot Simmediately after the time slot Sthrough the uplink signal US is transmitted, transmission of the downlink signal DS can be induced such that the response signal is positioned within the blank period BP same as that of the time slot S. Consequently, the sensor controllerthat detects a stylusby periodically transmitting an uplink signal US and detecting a downlink signal DS can obtain a downlink signal DS within a period that is not influenced by the liquid crystal noise LCDnz as soon as possible before the stylusis brought into contact with the operation panelon which the stylusis being pen down operated. It is to be noted that, if the liquid crystal noise LCDnz is not influenced by detection of an uplink signal US by the stylus, then only the transmission timingmay be included in the blank period BP.

701 2 4 0 1 2 2 702 3 5 2 2 2 0 19 2 The transmission timingindicates the time slot Sor Sexpressly designated by a command CC_UP with reference to the reference time point (S) given by the uplink signal US and the used efficiency fto the stylus(B) detected already. The transmission timingindicates the time slot Sor Sexpressly designated by the command CC_UP and the used frequency fto the stylus(C) detected already. The reason why a forward time slot as near as possible to a time point at which an uplink signal US is transmitted from among the 20 time slots Sto Sis used is that it is intended to perform such control that, even if only one blank period BP can be obtained within an a refresh cycle VT, a downlink signal DS from the stylusis received at a time point that may be included in a blank period BP with possibility as high as possible.

2 4 The command CC_UP may include a type of a signal to be transmitted such that the data signal OD_DP is included in the time slot Sand the position signal D_DP is included in the time slot S.

Where a plurality of blank periods BP exist in one refresh cycle VT, an uplink signal US may be transmitted within at least one blank period BP to wait for a response of a downlink signal DS, and a command CC_UP may be transmitted such that a data signal OD_DP is transmitted within a different blank period BP.

1 31 2 31 33 31 2 33 2 2 33 As described above, according to the position inputting system, sensor controllerand stylusas well as the method performed by them according to the present embodiment, since the sensor controlleracquires a refresh cycle VT at present of the liquid crystal panel, it is possible for the sensor controllerto transmit an uplink signal US, which makes a reference for synchronization corresponding to the acquired refresh cycle VT, to the stylus. Accordingly, it is possible to convey a preferable transmission timing of a signal according to a state of the liquid crystal panelto the stylus, which sends back a downlink signal DS at a timing designated as the reference time point for synchronization given by the uplink signal US. Especially, a signal transmitted from the stylusthat is in a pen down operated state can be detected at an early stage within a period within which the detection is not influenced by an action of the liquid crystal panel.

1 1 45 34 33 34 33 Now, a second embodiment of the present disclosure is described. A principal difference between the position inputting systemof the present embodiment and the position inputting systemaccording to the first embodiment is that a row electrode groupof a sensor boardis used commonly as a common electrode of a liquid crystal panel, namely, that a sensor board(or liquid crystal panel) of the in cell type is used. In the following, common constituent elements between the present embodiment and the first embodiment are denoted by like reference symbols and description of them is omitted, and description is given principally of the different of the present embodiment from the first embodiment.

9 9 FIGS.A andB 9 FIG.A 9 FIG.B 33 34 33 34 45 50 45 45 45 33 45 45 45 a c a c are a schematic views depicting a structure of the liquid crystal panelserving also as the sensor boardaccording to the present embodiment. As depicted in, the liquid crystal panelserving also as the sensor boardhas a row electrode groupformed on an upper face of a liquid crystal layer. As depicted in, the row electrode groupis configured from a plurality of row electrodestoextending in a Y direction (one direction in a display face of the liquid crystal panel). It is to be noted that, although the tree row electrodestoare exemplified here, the row electrode groupis actually configured from a greater number of row electrodes.

45 2 2 45 33 33 45 45 33 The row electrode groupserves, when a signal is to be transmitted toward the stylusand a finger touch is to be detected, as transmission electrodes (Tx), but serves, when a signal from the stylusis to be received, as reception electrodes (Rx), as described in the first embodiment. Further, the row electrode groupserves also as common electrodes of the liquid crystal panel, and when the liquid crystal panelis driven, a fixed potential Vcom is supplied to the row electrode group. The three roles described above of the row electrode group, namely, the role as the transmission electrodes (Tx), the role as the reception electrodes (Rx) and the role as common electrodes (Vcom) of the liquid crystal panelare implemented by time divisionally.

45 51 46 51 46 46 46 33 46 46 46 46 33 46 46 52 9 FIG.B a c a c As an upper layer on the row electrode group, a color filter glass plateis arranged with a transparent insulating layer not depicted interposed therebetween, and the column electrode groupis arranged on an upper face of the color filter glass plate. As depicted in, the column electrode groupis configured from a plurality of column electrodestoextending in an X direction (direction orthogonal to the Y direction in the display face of the liquid crystal panel). It is to be noted here that, although the three column electrodestoare exemplified, the column electrode groupis actually configured from a greater number of column electrodes. The column electrode groupdoes not serve as electrodes of the liquid crystal panel, but normally functions as reception electrodes (Rx) similarly to the column electrode groupdescribed hereinabove in connection with the first embodiment. As an upper layer on the column electrode group, a polarizeris arranged with a transparent insulating layer not depicted interposed therebetween.

10 FIG. 10 FIG. 3 FIG. 60 3 3 31 32 30 60 is a schematic block diagram depicting function blocks of a control deviceprovided in the electronic apparatusaccording to the present embodiment. As recognized through comparison ofwith, in the electronic apparatusaccording to the present embodiment, the sensor controller, liquid crystal driving circuitand electronic apparatus control circuitthat are provided separately from each other in the first embodiment are incorporated as a single control device.

60 61 62 40 41 42 61 30 32 61 33 The control deviceis configured including a control circuitand an indicator detection circuitin addition to the oscillation circuit, transmission circuitand reception circuitdescribed hereinabove in connection with the first embodiment. The control circuitfirst has functions of the electronic apparatus control circuitand the liquid crystal driving circuitdescribed hereinabove in connection with the first embodiment. In particular, the control circuithas a function for generating a driving signal LD described hereinabove on the basis of a video signal V obtained by reproducing a video image signal recorded, for example, on a storage medium not depicted and supplying the driving signal LD to the liquid crystal panel.

61 44 61 33 44 61 61 The control circuithas also a function as a refresh cycle acquisition circuitdescribed hereinabove in connection with the first embodiment. In particular, the control circuithas a function for extracting a refresh cycle VT indicative of a cycle of control of the liquid crystal paneland a blank period BPa that is a period within which the appearance frequency of liquid crystal noise LCDnz is low. However, since, different from the refresh cycle acquisition circuit, the control circuititself generates a driving signal LD, the process for extracting a refresh cycle VT and a blank period BPa is completed inside the control circuitand it is not necessary to monitor the liquid crystal noise LCDnz.

5 FIG. 32 Therefore, the blank period BPa according to the present embodiment is a period different from the blank period BP in the first embodiment. In particular, as described hereinabove with reference to, the blank period BP in the first embodiment is a period within which the liquid crystal driving circuitgenerates a driving signal LD corresponding to a vertical direction non-displaying area NDA and is a period corresponding to the vertical blanking period VB.

34 31 32 34 31 32 60 31 2 In contrast, the blank period BPa in the present embodiment is a period within which a driving process for a pixel is not performed within the latter half of a horizontal blanking period HB (Horizontal Blanking), namely, within a period within which the pixel of a driving target is returned from the right end to the left end of the screen. Since the blank period BPa is a very short time period in comparison with the blank period BP, this cannot be utilized effectively in the first embodiment in which the sensor boardof a system of the out cell type is implemented by an IC in which the sensor controllerand the liquid crystal driving circuitare separate from each other. However, this can be utilized effectively in the present embodiment in which the sensor boardof a system of the in cell type (or a system of the on cell type) that is configured from an integrated circuit in which the sensor controllerand the liquid crystal driving circuitare integrated with each other and can adjust the refresh timing strictly is implemented. Although details are hereinafter described, the blank period BPa appears many times repetitively within one refresh cycle VT from its nature. In the present embodiment, each of the blank periods BPa appearing many times in this manner is enumerated as a blank period BP that appears within a cycle of the refresh rate Rr to implement communication between the control deviceas the sensor controllerand the stylus.

11 FIG.A 7 FIG. 11 FIG.A 11 FIG.A 45 45 2 2 45 60 31 2 2 is a view depicting an example of arrangement of a blank period BPa in the present embodiment. A refresh cycle VT corresponds to a time period (image frame time period) within which displaying of one image frame is performed as illustrated also in, and as depicted in, the refresh cycle VT is configured so as to start together with activation of a video image synchronizing signal Vsync that is a pulse signal. In the example of, the refresh cycle VT includes a first number of (525) horizontal blanking periods HB, the latter half of each of the horizontal blanking periods HB can be utilized as a blank period BPa. Accordingly, 525 blank periods BPa are arranged discretely in an equidistantly spaced relationship from each other in one refresh cycle VT. Since it is necessary to drive a pixel at a timing other than the blank period BPa, the potential of the row electrode groupis fixed to the fixed potential Vcom described hereinabove. Accordingly, the row electrode groupcannot be used for the object of detection of a finger touch, transmission of a signal toward the stylus, reception of a signal from the stylusand so forth. On the other hand, within a blank period BPa, the potential of the row electrode groupis not fixed particularly. Therefore, the control deviceis configured such that it executes actions as the sensor controllerdescribed hereinabove in connection with the first embodiment such as detection of a finger touch, transmission of a signal toward the stylus, reception of a signal from the stylusand so forth utilizing the blank period BPa. It is to be noted that, as regards the number or the arrangement method of blank periods BPa within one refresh cycle VT, various ones may available such that they increases as the resolution with which they are compatible becomes higher like quadruple/quarter full high definition (QHD) or full high definition (HD) or conversely the number of blank periods PBa is intensively reduced to several tens.

10 FIG. 61 61 33 61 33 61 33 61 33 61 62 Referring back to, the control circuithas stored therein in advance a plurality of prescribed refresh cycles VT and arrangement methods of a plurality of prescribed blank periods BPa and selects one refresh cycle VT and one arrangement method in order to generate a driving signal LD. As a concrete example, the control circuithas stored therein in advance two refresh cycles VT of 60 Hz and 48 Hz, and where the liquid crystal panelis connected to an AC power supply, the control circuitselects 60 Hz, but where the liquid crystal panelis driven by a battery, the control circuitselects 48 Hz. The reason why the refresh cycle VT is lowered where the liquid crystal panelis driven by a battery in this manner is that it is intended to reduce the power consumption. Further, as an arrangement method of the blank period BPa, the control circuitstores an arrangement method in which a first number of (for example, 525) blank periods BPa are arranged in one refresh cycle VT and another arrangement method in which a second number (number different from the first number) of blank periods BPa are arranged within one refresh cycle VT, and selects one of the arrangement methods in response to a type of the liquid crystal panelor the like. The control circuitgenerates a driving signal LD in response to the selected refresh cycle VT and arrangement method of the blank period BPa and supplies the selected refresh cycle VT and arrangement method of the blank period BPa to the indicator detection circuit.

62 2 2 62 The indicator detection circuitperforms detection of a finger touch, transmission of a signal toward the stylus, reception of a signal from the stylusand so forth utilizing a plural number of blank period BPa included in a refresh cycle VT. The indicator detection circuitis configured such that it repetitively performs the mentioned processes in one set in a circuit of one refresh cycle VT.

11 11 FIGS.B andC 11 11 FIGS.A andC 11 FIG.B 11 FIG.C 62 1 1 1 525 1 2 2 are views depicting examples of a manner of use of the blank period BPa by the indicator detection circuitin the case where a first number L(as an example, L=525) of blank periods BPa are arranged within one refresh cycle VT. In, time periods Tto Tindividually corresponding to the first number Lof blank periods BPa and communication performed within individual blank periods BPa are depicted.depicts an example before a stylusis detected, andillustrates allocation of transmission of N position signals D_DP and M data signals OD_DP after a stylusis detected.

2 62 1 129 257 513 2 11 FIG.B First, when a stylusis not detected as yet, the indicator detection circuittransmits an uplink signal US in which a search pattern D_UP is included at a plurality of time periods T, T, T, . . . , Tas depicted in. This search pattern D_UP includes a sequence number indicative of what numbered search pattern the search pattern D_UP is such that a stylusreceiving this can acquire a reference time point for a refresh cycle VT.

12 FIG. 12 FIG. 0 2 0 2 is a view depicting an example of a configuration of the uplink signal US configured in this manner. The uplink signal US according to the example ofis configured including, in order from the top, two auxiliary uplink signals US sub, three command signals CCto CCand a cyclic redundancy code CRC generated from the command signals CCto CC.

2 33 2 2 2 One auxiliary uplink signal US sub is a signal including a search pattern D_UP of one bit known in advance to a stylus. The uplink signal US including a search pattern D_UP or a command CC_UP of a plurality of bits is an uplink signal US that is to make a reference for synchronization corresponding to the refresh cycle VT of the liquid crystal panelat present similarly as in the first embodiment, and the auxiliary uplink signal US sub plays a role of notifying a stylusof individual time points of a plurality of existing individual blank periods BPa and transmission timings of the downlink signal DS within the individual blank periods BPa. This is because it is intended to notify a stylusof individual patterns of blank periods BPa, which become different depending upon the situation of liquid crystal driving, without the necessity for sharing the individual patterns with the stylusin advance. One auxiliary uplink signal US sub is a signal for a short time period in comparison with the uplink signal US, and it becomes possible to receive a downlink signal DS within one blank period BPa.

2 Although the blank period BPa in the second embodiment is a short time period in comparison with the blank period BP in the first embodiment, since the auxiliary uplink signal US sub is a signal of a time length corresponding to one bit, a time period within which the stylustransmits a downlink signal DS in response to the auxiliary uplink signal US sub can be secured within one blank period BPa.

2 2 It is to be noted that the auxiliary uplink signal US sub is transmitted in a state in which a frequency of a signal generated by a spread code of a predetermined chip number is spread. The stylusis configured such that, by executing a correlation process for a known spread code transmitted in this manner, arrival of the auxiliary uplink signal US sub is detected. The reason why the auxiliary uplink signal US sub is transmitted twice is that it is intended to make it possible for the stylusto distinguish an uplink signal US for identifying a frame of the refresh cycle VT and an auxiliary uplink signal US sub for indicating an individual blank period BPa from each other.

0 2 2 0 2 0 2 0 2 0 2 2 0 2 0 2 2 60 60 2 12 FIG. The command signals CCto CCare signals each indicating a command CC_UP to be conveyed to the stylus. Though not depicted in, also the command signals CCto CCare transmitted in a state in which they are spread by a spread code of a predetermined chip number similarly to the auxiliary uplink signal US sub. It is to be noted that the information amount indicated by each of the command signals CCto CCdiffers depending upon a manner of use of the spread code. For example, where one bit is represented by inversion/non-inversion of the spread code, each of the command signals CCto CCrepresents information of one bit. On the other hand, where a spread code is used by cyclically shifting, each of the command signals CCto CCcan represent a greater number of bits. In any case, the stylushas stored in advance therein all spread codes that may possibly be received and is configured such that, by executing a correlation process between each of the spread codes and a reception signal, it receives the command signals CCto CC. The command CC_UP conveyed through the command signals CCto CCincludes information indicative of a refresh cycle VT (for example 48 Hz or 60 Hz), information indicative of an arrangement method of the blank period BPa (for example, whether the first number or the second number of blank periods BPa are arranged within one refresh cycle VT), information indicative of data to be sent from the stylusto the control device(that one of operation state data OD and configuration data CD described hereinabove in connection with the first embodiment, which is required by the control device), information indicative of a blank period BPa to be used for transmission of data by the stylusand so forth.

0 2 The cyclic redundancy code CRC is a code indicative of a remainder when data indicated by the command signals CCto CCis regarded as a numerical value and this is divided by a predetermined constant.

11 FIG.B 12 FIG. 2 2 128 1 129 513 62 62 2 2 2 60 2 Referring back to, when a stylusis not detected as yet, within the time periods Tto Tand so forth other than the time periods T, T, . . . , T, the indicator detection circuitperforms transmission of an auxiliary uplink signal US sub. The substance of the auxiliary uplink signal US sub transmitted here is same as that of the auxiliary uplink signal US sub within the uplink signal US described hereinabove with reference to. Though not depicted, the indicator detection circuitperforms such transmission of a single auxiliary uplink signal US sub at least once at the top of all of the time periods including those after detection of a stylus. By transmitting an uplink signal US and an auxiliary uplink signal US sub in combination in this manner, while a command CC_UP is conveyed to the stylusby the uplink signal US, by receiving a position signal D_DP at an early stage from the stylusthat receives the auxiliary uplink signal US sub, the control devicecan detect the stylusas early as possible.

2 60 2 62 2 2 1 2 1 2 128 130 256 1 2 5 2 130 133 2 1 6 128 2 134 256 2 62 11 FIG.C 11 FIG.C 11 FIG.C The stylusreceiving the auxiliary uplink signal USsub transmits a position signal D_DP for notifying the control deviceof presence of the stylusitself at an early stage. The indicator detection circuitthat receives the position signal D_DP from the stylusdetermines that the stylusis detected already and changes the method of use of later time periods as depicted in. In particular, only the time period Tpositioned at the top of one frame is used as the “first blank period” within which the uplink signal US described hereinabove is to be transmitted, and at least one of the remaining time periods is used as the “second blank period” within which the downlink signal DS is to be transmitted by the stylus. In the example of, the time periods to be used as the “second blank period” within Lblank periods are the time periods Tto T, Tto Tand so forth. More particularly, totaling N time periods including Ntime periods of the time periods Tto Tand Ntime periods Tto Tand so forth are utilized by the stylusto transmit a position signal D_DP. Meanwhile, totaling M time periods including Mtime periods Tto T, Mtime periods Tto Tand so forth are utilized by the stylusto transmit a data signal OD_DP including operation state data OD and so forth. In the following description, a data signal OD_DP transmitted within an mth (m is an integer from 1 to 492) time period among the M time periods is sometimes represented as data signal Dm as depicted in. The other time periods are used by the indicator detection circuitto detect a finger touch.

13 FIG. 2 6 2 illustrates an example of the auxiliary uplink signal US sub and the downlink signal DS in the case where the stylusperforms transmission of the data signal OD_DP within the time period Tas an example. Though not depicted, this similarly applies also to the other case in which the stylusperforms transmission of the data signal OD_DP within any other time period.

13 FIG. 6 62 2 1 4 As depicted in, at the top of the time period T, an auxiliary uplink signal US sub including a search pattern D_UP of one bit is transmitted once by the indicator detection circuit. In response to reception of the auxiliary uplink signal US sub once, the stylusstarts transmission of a data signal OD_DP within the remaining time period of the blank period BPa. For example, data datato dataof four bits are transmitted at once.

11 11 11 FIGS.A,B, andC 11 FIG.C 2 1 2 2 Referring back to, in the example of, 492 time periods for transmitting a data signal OD_DP are secured. The stylusis configured such that it transmits data of the first type (for example, the configuration data CD) within the Mtime periods from among the 492 time periods and transmits operation state data OD within the M(M≥0) time periods. This is described below in connection with a particular example.

14 FIG.A 2 FIG. 1 2 1 2 26 1 3 depicts an example where M=0 and M=492. In the present example, data Sand Sof two bits indicative of on/off states of the operation inputting circuitdepicted inand data indicative of a writing pressure F are transmitted using six data signals Dto D.

1 26 3 4 1 26 60 1 4 2 1 4 3 In particular, the data Sindicative of an on/off state of the operation inputting circuitis transmitted using the data dataand dataof the data signal D. Consequently, an on/off state of the operation inputting circuitis conveyed to the control devicetwice within one refresh cycle VT. However, this is a configuration for providing redundancy. The writing pressure F is transmitted using the data datato dataof the data signal Dand the data datato dataof the data signal D.

14 FIG.A 1 2 60 60 1 2 1 1 Here, as exemplified in, the data Sand the writing pressure F may be transmitted from the stylusto the control deviceby the number of times equal to or more than twice within one refresh cycle VT. Consequently, since the control devicecan receive the data Sand the writing pressure F with a higher frequency, it is possible to reproduce the width of a handwriting of the styluswith a higher degree of accuracy. In this case, preferably the transmission timing of the data Sand the writing pressure F is set such that the data Sand the writing pressure F are transmitted individually after equal time intervals.

14 FIG.B 1 2 1 7 depicts an example in which M=5 and M=2. In the present example, the stylus identifier SID and the writing pressure F are transmitted using all of the data signals Dto D.

1 5 6 7 More particularly, first the stylus identifier SID is transmitted using the data signals Dto D. However, since the data amount is excessively great and the data cannot be transmitted only within one refresh cycle VT, it is transmitted over a plurality of successive refresh cycles VT. On the other hand, the writing pressure F is transmitted using the data signals Dand D. Consequently, in the present example, data for eight bits indicative of the writing pressure F is transmitted once within every refresh cycle VT.

62 2 2 62 2 2 1 5 60 60 26 14 FIG.B Here, the stylus identifier SID is information which may be sent only once when the indicator detection circuitdetects a stylus. Accordingly, initially when a stylusis detected by the indicator detection circuit, after the stylustransmits its stylus identifier SID once using the time periods as depicted in, the styluspreferably uses also the data signals Dto Dfor transmission of the writing pressure F. By this, after the stylus identifier SID is conveyed once to the control device, it becomes possible to send the writing pressure F with a high frequency, and also it becomes possible to notify the control deviceof an on/off state of the operation inputting circuitor a state of the battery.

62 2 Now, processes performed by the indicator detection circuitand the stylusaccording to the present embodiment are described more particularly again with reference to respective processing flow diagrams.

15 FIG. 11 11 FIGS.B andC 62 is a processing flow diagram illustrating processes performed by the indicator detection circuit. Although this processing flow assumes the arrangement method of the blank period BPa depicted, also where a different arrangement method is used, the processing flow similarly applies although processes performed within individual time periods are replaced.

62 33 1 62 1 2 2 62 2 45 46 3 The indicator detection circuitfirst acquires a refresh cycle VT of the liquid crystal paneland an arrangement method of the blank period BPa within the refresh cycle VT (S). Then, the indicator detection circuituses the time period Tto transmit an uplink signal US including a command CC_UP that indicates the acquired refresh cycle VT and arrangement method of the blank period BPa (S). Thereafter, within the next time period T, the indicator detection circuittransmits an auxiliary uplink signal USsub and executes detection of a position signal D_DP transmitted from an unknown stylususing all of the electrodes that configure the row electrode groupand the column electrode group(full scan) (S).

62 4 5 2 6 3 62 7 62 2 2 The indicator detection circuitdecides whether or not a position signal D_DP is detected (S), and if it decides that a position signal D_DP is detected, then it sets a pen detection flag (S) and analyzes the position of the stylusfrom the detected signal (S). On the other hand, if it is decided at Sthat a position signal D_DP is not detected, then the indicator detection circuitresets the pen detection flag (S). It is to be noted that the pen detection flag is an internal flag of the indicator detection circuit, and while a stylusremains detected, the pen detection flag indicates the set state, but while a stylusis not detected, the pen detection flag indicates the reset state.

2 2 1 129 257 385 513 2 2 129 257 385 513 3 6 2 3 5 130 133 258 262 386 389 The process at Sfrom among the described above is performed, when a stylusis not detected as yet, similarly as in the time period T, also within the other time periods T, T, Tand Tallocated to transmission of the uplink signal US. On the other hand, if a stylusis detected already, then the process at Sis not performed within the other time periods T, T, Tand T. Further, the processes at Sto Sare performed similarly as in the time period Talso within the other time periods Tto T, Tto T, Tto Tand Tto Tallocated to reception of the position signal D_DP.

6 62 8 2 62 9 62 10 Within the time period T, the indicator detection circuitfirst confirms the pen detection flag (S), and if the pen detection flag is in the set state (namely, if a stylusis detected), then the indicator detection circuitperforms a data reception process (S). On the other hand, if the pen detection flag is in the reset state, then the indicator detection circuitperforms only transmission of an auxiliary uplink signal US sub (S).

16 FIG. 16 FIG. 9 62 20 6 45 46 62 21 62 2 22 62 62 is a processing flow diagram illustrating details of the data reception process performed at S. As depicted in, the indicator detection circuitfirst transmits an auxiliary uplink signal US sub and executes detection of a data signal OD_DP (S) utilizing only electrodes in the proximity of the position detected at Sfrom within the row electrode groupand the column electrode group(local scan). Then, the indicator detection circuitdecides whether or not some signal is detected as a result of the execution of the detection (S). Then, if it is decided that some signal is detected, then the indicator detection circuitdemodulates the detected signal to acquire the data transmitted from the stylus(S), whereafter the indicator detection circuitends the data reception process. On the other hand, if it is decided that no signal is detected, then the indicator detection circuitparticularly performs nothing and ends the data reception process.

15 FIG. 8 10 6 6 128 134 256 262 384 390 512 Referring back to, the processes at Sto Sare performed similarly as in the time period Talso within time periods actually used for reception of a data signal OD_DP from among the other time periods Tto T, Tto T, Tto Tand Tto Tallocated to reception of the data signal OD_DP.

514 62 45 46 11 Within the time period T, the indicator detection circuitperforms detection of a finger touch using all of the electrodes configuring the row electrode groupand the column electrode group(full scan) (S).

62 11 12 62 13 12 62 The indicator detection circuitdecides whether or not a signal of a finger touch is detected by the full scan at S(S), and if it is decided that a signal of a finger touch is detected, then the indicator detection circuitanalyzes the position of the finger from the detected signal (S). On the other hand, if it is decided at Sthat a signal of a finger touch is not detected, then the indicator detection circuitadvances its processing to a next time period without performing any process especially.

11 13 514 513 525 The processes at Sto Sare performed similarly as in the time period Talso within the other time periods Tto Tallocated to detection of a finger.

62 1 525 1 525 1 2 2 11 11 11 FIGS.A,, andC In this manner, the indicator detection circuitrepetitively performs processes allocated to the time periods Tto Tdepicted inin the order of the time periods Tto T. Further, if a new refresh cycle VT is entered, then the processes beginning with the process at Sare repeated. Consequently, acquisition of a refresh cycle VT and an arrangement method of the blank period BPa, transmission of an uplink signal US, detection and position derivation of a stylus, reception of a data signal OD_DP transmitted from the stylus, and detection and position derivation of a finger touch are repeated time-divisionally.

17 FIG. 17 FIG. 2 2 30 31 2 30 31 is a processing flow diagram illustrating processes performed by a stylus. As depicted in, the stylusfirst performs sensing of an auxiliary uplink signal US sub (S) and decides whether or not an auxiliary uplink signal US sub is detected by the sensing (S). The stylusrepetitively executes the processes at Sand Swhile the power supply remains on.

31 2 32 33 30 33 30 2 12 FIG. If it is decided at Sthat an auxiliary uplink signal US sub is detected, then the stylussubsequently performs sensing of an uplink signal US including a search pattern D_UP (S) and decides whether or not an uplink signal US is detected by the sensing (S). This process is in short a process of deciding whether an auxiliary uplink signal US sub detected at Sis transmitted alone or is part of an uplink signal US (refer to). If it is decided at Sthat an uplink signal US is not detected, then the processing returns to S, at which the stylusperforms sensing of a next auxiliary uplink signal US sub.

33 2 34 2 60 60 2 2 If it is decided at Sthat an uplink signal US is detected, then the stylussubsequently analyzes a command CC_UP included in the detected uplink signal US and updates downlink parameters on the basis of a result of the analysis (S). The downlink parameters are in short various kinds of information included in the command described hereinabove, namely, information indicative of a refresh cycle VT (for example, 48 Hz or 60 Hz), information indicative of an arrangement method of the blank period BPa (for example, whether the first number or the second number of blank periods BPa are to be arranged within one refresh cycle VT), information indicative of data to be sent from the stylusto the control device(that one of the operation state data OD and the configuration data CD described hereinabove in connection with the first embodiment which is required by the control device), information indicative of a blank period BPa to be used for transmission of data by the stylusand so forth, and the stylusretains the received downlink parameters until new downlink parameters are received subsequently.

2 35 36 2 37 Then, the stylusexecutes sensing of an auxiliary uplink signal US sub again (S) and decides whether or not an auxiliary uplink signal USsub is detected by the sensing (S). As a result, if it is decided that an auxiliary uplink signal US sub is detected, then the stylusperforms transmission of a downlink signal DS, which is a position signal D_DP or a data signal OD_DP that includes data indicated by the downlink parameters at a timing according to the auxiliary uplink signal USsub (S).

36 2 38 2 39 2 2 If it is decided at Sthat an auxiliary uplink signal US sub is not detected, then the stylusdecides whether or not a transmission timing indicated by the downlink parameters comes (S), and if it is decided that a transmission timing comes, then the stylusperforms transmission of a downlink signal DS (S). This process is a process for preventing transmission of a downlink signal DS from being skipped by a reception miss of the auxiliary uplink signal US sub. In particular, the styluscan predict a timing at which a downlink signal DS is to be transmitted next on the basis of the refresh cycle VT and the arrangement method of the blank period BPa included in the downlink parameters. Therefore, even when an auxiliary uplink signal US sub is not received, if the predicted timing comes, then the stylustransmits a downlink signal DS.

38 2 35 If it is decided at Sthat the transmission timing indicated by the downlink parameters does not come as yet, then the stylusreturns its processing to S, at which it performs sensing of an auxiliary uplink signal US sub again.

37 39 2 40 2 35 40 2 30 After a downlink signal DS is transmitted at Sor S, the stylusdecides on the basis of the downlink parameters retained therein whether or not a reception timing of an uplink signal US comes (S). As a result, if it is decided that a reception timing does not come, then the stylusreturns the processing to Sin order to transmit a next downlink signal DS. On the other hand, if it is decided at Sthat a reception timing comes, then the stylusreturns the processing to S. Consequently, similar processes are repeated for every refresh cycle VT.

1 31 2 60 33 60 2 33 2 As described above, with the position inputting system, sensor controller, and stylusas well as the method performed by them according to the present embodiment, since the control deviceas a sensor controller acquires a refresh cycle VT at present of the liquid crystal panel, it is possible for the control deviceto transmit an uplink signal US, which makes a reference for synchronization corresponding to the acquired refresh cycle VT, to the stylus. Accordingly, it is possible to convey a preferable transmission timing of a signal according to a state of the liquid crystal panelto the stylus.

2 Further, since the uplink signal US includes information indicative of an arrangement method of the blank period BPa, the styluscan transmit a downlink signal DS within a blank period BPa in which noise is low.

Although preferred embodiments of the present disclosure are described, the present disclosure is not limited to the embodiments at all, and it is a matter of course that the present disclosure can be carried out in various modes without departing from the subject matter thereof.

62 2 2 2 17 FIG. For example, while the second embodiment described above is directed to an example in which the indicator detection circuittransmits an auxiliary uplink signal US sub at the top of each time period, such transmission of an auxiliary uplink signal US sub is not always necessary. In particular, since a refresh cycle and an arrangement method of the blank period BPa are conveyed in advance to the stylusby an uplink signal US as described hereinabove with reference to, the styluscan know a start timing of each time period even if an auxiliary uplink signal USsub is not available. Accordingly, even if the stylusdoes not receive an auxiliary uplink signal US sub, it can perform transmission of a downlink signal DS at an appropriate timing. Since there is the possibility in the first place also that an auxiliary uplink signal USsub may fail to be received, preferably it is positioned as an element for auxiliarily conveying a start of a time period.

62 2 Since transmission of the auxiliary uplink signal US sub is arbitrary in this manner, the command CC_UP included in the uplink signal US may include information indicative of whether or not the indicator detection circuitis to perform transmission of an auxiliary uplink signal US sub. By referring to this information, the styluscan determine whether or not, when a downlink signal DS is to be transmitted, it is to wait an auxiliary uplink signal US sub.

33 It is to be noted that, while the foregoing embodiments are described taking the liquid crystal panelas an example, the present disclosure can be applied also to display panels for which a display panel of a different type such as an organic EL panel is applied. More particularly, the present disclosure can be applied to a bidirectional communication system that uses an active stylus utilized together with a display panel in which each cycle of a refresh rate includes a display refresh period and one or more blank periods.

1 Position inputting system 2 Stylus 3 Electronic apparatus 20 Electrode 21 Transmission/reception switching circuit 22 Oscillation circuit 23 Transmission circuit 24 Reception circuit 25 Operation information detection circuit 26 Operation inputting circuit 27 Configuration information storage circuit 28 Communication control circuit 30 Electronic apparatus control circuit 31 Sensor controller 32 Liquid crystal driving circuit 33 Liquid crystal panel 34 Sensor board 35 Operation panel 40 Oscillation circuit 41 Transmission circuit 42 Reception circuit 43 Indicator detection circuit 44 Refresh cycle acquisition circuit 45 Row electrode group 45 45 a c toRow electrode 46 Column electrode group 46 46 a c toColumn electrode 47 Transmission/reception switching circuit 50 Liquid crystal layer 51 Color filter glass plate 52 Polarizer 60 Control device 61 Control circuit 62 Indicator detection circuit 700 Transmission timing of uplink signal US 701 702 ,Transmission timing of configuration data CD and operation state data OD 719 Response timing to uplink signal US BP, BPa Blank period CC_UP Command CD Configuration data 1 CRTbCommunication resource table D_DP Position signal (response signal) D_UP Search pattern DA Display area DS Downlink signal F_sel Frequency setting signal HB Horizontal blanking period HI Horizontal synchronization cycle HSYNC Horizontal synchronizing signal LCDnz Liquid crystal noise LD Driving signal ND Noise period NDA Vertical direction non-displaying area NF Noise-free period NP Noise period OD Operation state data 1 492 OD_DP, Dto DData signal Pos Position information Rr Refresh rate S_sel Switching signal US Uplink signal USsub Auxiliary uplink signal V Video signal VB Vertical blanking period Vcom Fixed potential Vsync Video image synchronization signal 1 2 VT, VT, VTOperation period